JP2003077839A - Purging method of semiconductor-manufacturing apparatus and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purging method of a semiconductor-manufacturing apparatus, such as a CVD apparatus for shortening a time required for purge, for improving operating efficiency in the apparatus, and for increasing productivity, and to provide a manufacturing method of a semiconductor device using the purged semiconductor-manufacturing apparatus. SOLUTION: The inside of a reaction bath 2 which constitutes a semiconductor-manufacturing apparatus, where a CVD film is subjected to film-formed treatment on a semiconductor wafer by a CVD method is subjected to dry cleaning by cleaning gas containing halogen such as ClF3 . In a succeeding purging (substitution removal) process, gas containing hydrogen (1), gas containing vapor (2), and gas containing a material that reacts with water such as ammonia (3), and that turns into a base is used as the gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purging process for semiconductor manufacturing equipment, and more particularly to a CVD (Chemical Vapor
eposition) Purge after dry cleaning of equipment.

[0002]

2. Description of the Related Art Semiconductor manufacturing equipment such as LP (Low Pre
A CVD device such as ssure) -CVD is used to deposit a thin film of silicon, silicon oxide, silicon nitride or other thin film used in a semiconductor device in a reaction tank.
A deposited film is deposited. If such a CVD deposited film becomes too thick, there is a problem that film peeling occurs and dust contamination occurs. Also, if the deposited film in the reaction tank has an uneven film thickness, it is formed on a semiconductor wafer. There is a problem that the formed CVD film is not formed uniformly. Therefore, conventionally, the deposited film has been removed by an etching treatment with a cleaning gas containing halogen such as ClF ₃ or F ₂ before such a problem does not become noticeable. Normally, dry cleaning was started when the accumulated film thickness on the monitor wafer exceeded a certain level, and dry cleaning was carried out for a period of time that was empirically determined to be sufficient. Thus, C
As a method of dry cleaning the deposited film attached inside the VD chamber (reaction tank), for example, an etching gas such as ClF ₃ is used. After cleaning such a chamber, it is necessary to completely purge and remove the etching gas before performing the usual CVD process thereafter.

[0003]

[Problems to be Solved by the Invention] However, ClF
Etching gases such as ₃ contained halogen with high electronegativity, and those adsorbed on the chamber surface could not be easily desorbed even by purging, and as a result, long-term purging was required. A long purge time after cleaning is not a particular problem as long as the chamber is used with a low cleaning frequency, but in the case where cleaning must be performed every time the CVD process is performed, This leads to a decrease in throughput. The present invention has been made in view of the above circumstances, and a method of purging a semiconductor manufacturing apparatus such as a CVD apparatus and a method of purging the same for improving the operating rate of the apparatus and improving the productivity by shortening the purging time. A method for manufacturing a semiconductor device using the semiconductor manufacturing device purged by using the method is provided.

[0004]

According to the present invention, a cleaning gas containing halogen such as ClF ₃ is used in a reaction tank constituting a semiconductor manufacturing apparatus in which a CVD film is formed on a semiconductor wafer by a CVD method. It is characterized in that dry cleaning is performed, and then a gas containing the materials shown below (to), for example, nitrogen, argon, oxygen, or a mixture thereof is used in the subsequent purging (substitution removal) step. A material that becomes a base by reacting with water such as hydrogen, steam, and ammonia. That is, the semiconductor manufacturing apparatus purging method of the present invention is a cleaning gas containing at least a halogen gas for a CVD deposited film deposited in a reaction tank constituting a semiconductor manufacturing apparatus in which a CVD film is formed on a semiconductor wafer by a CVD method. After the step of etching and removing the CVD deposited film with a cleaning gas, a gas containing hydrogen is flown into the reaction tank to purge the cleaning gas remaining in the reaction tank. It is characterized by having a process.

Further, according to the purging method of the semiconductor manufacturing apparatus of the present invention, the CVD deposited film deposited in the reaction tank constituting the semiconductor manufacturing apparatus in which the CVD film is formed on the semiconductor wafer by the CVD method is subjected to at least halogen gas. Etching with a cleaning gas containing C, and
After the step of etching away the VD deposited film with a cleaning gas, a step of flowing a gas containing water vapor into the reaction tank to purge the cleaning gas remaining in the reaction tank is provided. It has a feature. Further, the purging method of the semiconductor manufacturing apparatus of the present invention uses C
CV deposited in a reaction tank constituting a semiconductor manufacturing apparatus in which a CVD film is formed on a semiconductor wafer by the VD method
After the step of etching away the D deposited film with a cleaning gas containing at least a halogen gas and the step of etching away the CVD deposited film with a cleaning gas, the reaction tank contains a substance that becomes an alkali when dissolved in water. And a step of purging the cleaning gas remaining in the reaction tank.

Further, according to the purging method of the semiconductor manufacturing apparatus of the present invention, at least the halogen gas is deposited on the CVD deposited film deposited in the reaction tank constituting the semiconductor manufacturing apparatus in which the CVD film is formed on the semiconductor wafer by the CVD method. Etching with a cleaning gas containing C, and
After the step of etching away the VD deposited film with a cleaning gas, a step of flowing an ammonia gas into the reaction tank to purge the cleaning gas remaining in the reaction tank is provided. . A method of manufacturing a semiconductor device according to the present invention comprises a step of inserting and mounting a semiconductor wafer in a reaction tank purged by the method for purging a semiconductor manufacturing device according to any one of claims 1 to 4, And a step of forming a CVD film on the semiconductor wafer in a reaction tank.

The present invention further includes claims 1 to 4.
The invention described in any one of the above may be configured as follows. (1) The completion of purging is determined by monitoring the residual gas remaining in the reaction tank. (2) Monitoring the residual gas by mass separation of the residual gas. (3) In the purging step, the exhaust speed is changed by repeating pressure fluctuations. (4) The pressure fluctuation value of the pressure fluctuation should be different by three digits or more. (5)
In the purging step, the temperature of the reaction tank and the exhaust pipe connected to the reaction tank is set higher than the temperature at which the CVD film is formed. (6) The residual gas remaining in the reaction tank is used as a doping gas in the next process.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described with reference to FIG. FIG. 1 is a vertical CVD which is a semiconductor manufacturing apparatus.
It is a schematic sectional drawing of an apparatus. A semiconductor wafer such as silicon is placed on the reaction vessel (hereinafter referred to as a chamber) 2 placed vertically so that it is used. A gas introduction port 1 is attached to the lower portion of the chamber 2, and the cleaning gas is introduced into the chamber 2 from here. A heater 3 is arranged outside the chamber 2 where the semiconductor wafer is placed in order to heat that portion. A pump 6 is connected to the chamber 2 through an exhaust pipe 4 having a pressure control valve 5, and the inside of the chamber 2 is appropriately exhausted.

Using the CVD apparatus shown in FIG. 1, LP-CV
After forming a silicon film by the D process, ClF ₃
Dry cleaning was performed using gas as a cleaning gas. Before dry cleaning, a silicon film was attached to the inside of the chamber (reaction tank) of the CVD apparatus by about 300 nm. After decompressing the chamber once, ClF diluted with 1600 sccm of nitrogen (N ₂ )
_{The 3} gas was supplied to the inside of the chamber kept at 900 sccm, the chamber temperature of 350 ° C. and the chamber pressure of 20 Torr, and reacted with the silicon deposited film inside the chamber to remove the silicon film inside the chamber by dry cleaning. Since the reaction between the ClF ₃ gas and the silicon film is an exothermic reaction, the end of cleaning can be judged from the change by monitoring the power of the chamber internal thermometer or the heater heating the chamber.

After the cleaning was completed, the supply of ClF ₃ gas and nitrogen was stopped, and the inside of the chamber was pulled out while the gas was not flowing at all, and the chamber was held for 2 minutes. The pressure at this time is 0.
It was 8 mTorr. After this, 5s inside the chamber
A mixed gas of 1 lm of nitrogen and 5 slm of hydrogen (H ₂ ) was flowed and held for 2 minutes. The pressure at this time is 100 Tor
It was r. This pulling step and the step of flowing the mixed gas are repeated, and as a result of performing the cycle purge three times in total, the residual gas of ClF ₃ cannot be detected by the monitor by the quadrupole mass meter (Q-mass) 7. It was confirmed. Also, Cl, F formed by decomposition of ClF ₃
None of these have been detected. On the other hand, for comparison, nitrogen is replaced by 10 sl instead of the mixed gas of hydrogen and nitrogen.
When monitoring was performed by Q-mass similarly in the case of m flow, it was confirmed that Cl and the like remained after the same number of repetitions as above, and sufficient purging was not performed.

[0011] Here Thus, it began to effectively the possible removal of ClF ₃ by purging with a gas containing hydrogen, with _{ClF 3 + 2H 2 → HCl +} 3HF ··· (1) The reaction shown occurs (see equation (1)) and residual ClF
_This is probably because ₃ was removed. Although the amount of hydrogen added was the same as that of nitrogen in this embodiment, it is not limited to this, and 100% hydrogen (that is, only hydrogen) may be used. The flow rate is set to 5 slm in this embodiment, but 500 sc
If it is at least cm, the effect of addition can be exhibited.
According to this embodiment, the purging can be shortened and the operating rate of the apparatus can be improved.

Next, a second embodiment will be described. In this example, as in the first example, cleaning was performed using ClF ₃ gas with the silicon film attached to the inside of the chamber. In purging after this cleaning, 5
In addition to slm nitrogen, 25 sccm of water vapor (H
₂ O) with mixed gas. At this time, the chamber pressure is 100 Torr, and thus the water vapor partial pressure is 0.5 Torr (that is, 0.5 mmHg). The cycle purge in which the pulling step and the gas flowing step similar to those in the first example was performed was repeated 5 times in total. Then, as a result of monitoring by Q-mass, ClF ₃
Residual gases such as HCl and HF, which are considered to be gas-derived,
It was confirmed that it was not seen at all. It was confirmed that HF and HCl remained in the same number of cycle purges when only nitrogen was passed without adding water vapor, which was carried out for comparison. Therefore, it can be determined that HF could be effectively removed.

As described above, HF and H are added by adding steam.
Cl was able to be removed because when ClF ₃ was allowed to flow, if there was water remaining inside the chamber, that water and ClF
_{This is because 3} reacts with ClF ₃ + 2H ₂ O → 3HF + HCl + O ₂ (2) Formula (2) produces HF and HCl. Therefore, by supplying water during purging, H
Since both F and HCl can be desorbed, residual HF and HCl
The amount can be reduced. However, in the purge with steam added, immediately after the purge,
Although the amount of residual HF and HCl can be reduced, on the contrary, water vapor remains. In order to avoid this, it is desirable to carry out purging with a gas containing water vapor and then purging with a gas containing no water vapor at all. As the conditions, for example, in the condition that the above-mentioned steam is added,
It suffices that the addition of water vapor is stopped.

Regarding the method of adding water at the time of purging, there is a "method of removing chlorine trifluoride gas" disclosed in Japanese Patent Application Laid-Open No. 5-331630. This publication discloses that it is desirable to use air or gas containing water vapor with a partial pressure of 1 mmHg or more as an addition amount. However, according to this example, it was confirmed that the addition of water vapor was effective even at a water vapor partial pressure lower than 1 mmHg. The effect is 0.
It was sufficient if the pressure was 05 Torr (= 0.05 mmHg) or more. Further, in the publicly known publication, only the process of adding water vapor to air or nitrogen is shown,
Actually, there is a problem that water vapor remains, so it is desirable to carry out purging with a gas to which water vapor is not added after purging after the addition of water vapor. According to this embodiment, the purging can be shortened and the operating rate of the apparatus can be improved.

Next, a third embodiment will be described. In this example, similarly to the first example, cleaning with ClF ₃ gas was performed with the silicon film attached inside the chamber. The purging after the cleaning was performed using a gas in which 100 sccm of water vapor was mixed in addition to 5 slm of nitrogen. As a result of repeating the cycle purging in which the pulling step and the gas flowing step similar to those in the first embodiment are performed 5 times in total, the result of monitoring by Q-mass, HF and HC which are considered to be caused by ClF ₃ gas
No residual gas such as l was observed at all, and similarly, cleaning was performed using ClF ₃ gas with the silicon film attached inside the chamber. The purging after the cleaning was performed by using a gas in which 500 sccm of ammonia (NH ₃ ) was mixed in addition to 2 slm of nitrogen. As a result of repeating the cycle purge in which the pulling step and the gas flowing step are repeated three times in total, the residual gas such as HCl and HF, which is considered to be caused by ClF ₃ gas, is not seen at all by the monitor by Q-mass. Was confirmed.

By adding ammonia in this way, HF and HCl could be removed because the HF and HCl formed by the reaction with the residual water inside the chamber when ClF ₃ was flowed was NH ₃ NH by reacting with
_This is because ₄ F and NH ₄ Cl are produced. As a result, HF and HCl, which are the acids remaining in the chamber,
Change to more stable salts NH ₄ F and NH ₄ Cl,
As a result, even if the metal portion inside the device was easily corroded, the concern of corrosion can be reduced.
Although ammonia was used as the additive gas in this example, any gas that reacts with HF or HCl and neutralizes with HF or HCl that is an acid may be used. For example, NaOH or KOH may be added to water. Any substance that becomes an alkali when melted may be used. According to this embodiment, the purging can be shortened and the operating rate of the apparatus can be improved.

Next, a fourth embodiment will be described with reference to FIGS. FIG. 2 is a characteristic diagram showing the dependency of the ion current on the number of purges. In this example, as in the case of the first example, cleaning was performed using ClF ₃ gas with the silicon film attached inside the chamber. Purging after this cleaning was performed by flowing nitrogen of 5 slm. As shown in FIG. 1, a quadrupole mass meter (Q-mass) 7 was set on the exhaust side of the chamber, and its change was examined. HF measured at each pulling step,
The change in peak intensity due to the Q-mass of the mass numbers of HCl and Cl is shown in FIG. It can be seen that by repeating the gas supply cycle seven times, no peaks were detected and sufficient purging was performed. By performing such monitoring, it is possible to perform the necessary and sufficient number of purges. In this embodiment, only nitrogen was used as the gas at the time of purging, but it is similarly effective when adding the gas as shown in the first to third embodiments, and in any case, the above It was confirmed that the residual F or Cl concentration was below the detection limit with the number of cycles less than 7, and it became possible to perform the necessary and sufficient number of times of time purging. According to this embodiment, the purging can be shortened and the operating rate of the apparatus can be improved.

Next, a fifth embodiment will be described. In this example, as in the first example, ClF ₃ was used to clean and remove the silicon film attached to the inside of the chamber while the silicon film was attached to the inside of the chamber. In the subsequent cycle purging step, with respect to the method of flowing nitrogen, the step of completely withdrawing nitrogen and the step of flowing nitrogen were repeated as in the first embodiment. In the step of flowing the nitrogen, in this embodiment, especially, 10 sl of nitrogen is used.
The conductance control on the exhaust side was performed so that the pressure was 400 Torr in the state of m flow. As a result, as compared with the case where the conductance control on the exhaust side is not particularly performed as shown in the first embodiment and the like, the result of monitoring by Q-mass is that the number of times the cycle purge is required is five, but only four is required. It was confirmed that The reason why the effect of increasing the pressure at the time of flowing the nitrogen appears is that the halogen is frequently desorbed because the nitrogen is frequently attacked with respect to the residual halogen adhering to the chamber wall and the like. The separation efficiency was improved, and a small number of cycle purges was sufficient.

In this example, the pressure at the time of pulling off was 1 mTorr, and the control pressure at the time of flowing nitrogen was 400 Torr, and the pressure difference was more than 5 digits. Comparing the purge efficiencies when controlling various pressures, it was confirmed that good purge efficiency can be realized when the pressure difference between the time of pulling off and the time of flowing nitrogen is 3 digits or more. According to this embodiment, the purging can be shortened and the operating rate of the apparatus can be improved.

Next, a sixth embodiment will be described. With the silicon film attached to the inside of the chamber, ClF ₃ gas was used to clean and remove the silicon film attached to the inside of the chamber. In the cleaning process, the chamber temperature was controlled at 400 ° C. and the exhaust pipe was controlled at 50 ° C., but in the subsequent purge step, the chamber temperature was controlled at 850 ° C. and the exhaust pipe temperature was controlled at 150 ° C.
By controlling the temperature to be higher than that in the cleaning step in this way, it is possible to improve the desorption efficiency of the adhered gas and the purging efficiency. Actually, as a result of monitoring by Q-mass in the same manner as in the above-mentioned example, it was confirmed that the number of cycle purges required to be 5 can be reduced to 4 only.

Although this embodiment describes the case of the cleaning gas using ClF ₃ , the same effect can be realized not only in the cleaning process but also in the CVD process as long as the process contains halogen as the source gas. For example, CVD or the like using SiH ₂ Cl ₂ as a source gas corresponds thereto. Further, in this embodiment, the chamber temperature in the purge step is 850.
℃, the exhaust pipe temperature was controlled at 150 ℃, but the temperature is not limited to this, how much the equipment can raise the temperature of each part, and the time required for raising and lowering the temperature. It can be applied by appropriately changing it depending on the degree. As described above, the effective purging methods have been shown from the first embodiment to the sixth embodiment, but it goes without saying that purging by a combination of these methods is also possible, and it is preferable to carry out each of them independently. Can achieve good purging efficiency. According to this embodiment, the purging can be shortened and the operating rate of the apparatus can be improved.

Next, a seventh embodiment will be described. With the deposited silicon film inside the chamber, ClF ₃ gas was used to clean and remove the deposited silicon film inside the chamber. After that, the interior of the chamber was purged with nitrogen. While confirming that HF remained by the monitor by Q-mass, using this chamber, 300 cc of silane gas was used.
A polycrystalline silicon film was deposited under the conditions of m, pressure 1 Torr, and temperature 600 ° C. The impurities contained in this film are treated as SI
When measured using MS, it was confirmed that F having a peak concentration of 10 ¹⁸ cm ⁻³ was present at the interface between the substrate and the deposited film. A gate electrode of a MOS capacitor was formed using this film, and the breakdown voltage of the created MOS capacitor was examined by TDDB measurement. As a result, as compared with the case where a polycrystalline silicon film containing no F was used as the gate electrode,
It was confirmed that the proportion of capacitors that became defective in a short time was decreasing.

Regarding the effect of such F, Y. Mitan
i et al., 1999 IEEE International Reliability Physics
Symposium Proceedings. 3 ^7th Annual (Cat. No. 99CH3
6296) (USA) PP93-8, it is considered that F has a function of compensating for defects existing in the gate oxide film. The method according to this embodiment simply removes the gas remaining in the chamber without increasing the number of process steps.
It can be said that an extremely excellent method can realize a structure having a merit on the device by leaving only the controlled amount. As described above, the semiconductor wafer such as silicon is inserted and fixed in the reaction tank of the semiconductor manufacturing apparatus (CVD apparatus) dry-cleaned by the purging method described in the embodiment. Then, in the reaction tank, a CVD film such as a silicon oxide film is deposited on the semiconductor wafer, and a post-treatment process is performed to form a semiconductor device.

[0024]

As described above, by improving the purging efficiency and shortening the purging time, the operating efficiency of the semiconductor manufacturing apparatus can be increased.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a CVD apparatus of the present invention.

FIG. 2 is a characteristic diagram showing a purge characteristic of the present invention.

[Explanation of symbols]

1 ... Gas inlet, 2 ... Chamber, 3 ...
・ Heater (for chamber heating), 4 ... Exhaust pipe, 5 ... Pressure control valve, 6 ... Pump, 7
... Quadrupole mass meter (Q-mass).

Claims (5)

[Claims] 1. A method for depositing C on a semiconductor wafer by a CVD method.
A step of etching and removing a CVD deposited film deposited in a reaction tank constituting a semiconductor manufacturing apparatus in which a VD film is formed by a cleaning gas containing at least a halogen gas; and a step of etching and removing the CVD deposited film with a cleaning gas. And a purge step for purging the cleaning gas remaining in the reaction tank by flowing a gas containing hydrogen into the reaction tank. 2. C on a semiconductor wafer by the CVD method
A step of etching and removing a CVD deposited film deposited in a reaction tank constituting a semiconductor manufacturing apparatus in which a VD film is formed by a cleaning gas containing at least a halogen gas; and a step of etching and removing the CVD deposited film with a cleaning gas. And a purge process for cleaning gas remaining in the reaction tank by flowing a gas containing water vapor into the reaction tank. 3. C on a semiconductor wafer by the CVD method
A step of etching and removing a CVD deposited film deposited in a reaction tank constituting a semiconductor manufacturing apparatus in which a VD film is formed by a cleaning gas containing at least a halogen gas; and a step of etching and removing the CVD deposited film with a cleaning gas. After that, a step of causing a gas containing a substance that becomes an alkali when dissolved in water to flow into the reaction tank to purge the cleaning gas remaining in the reaction tank is provided. Purge method for semiconductor manufacturing equipment. 4. C on a semiconductor wafer by the CVD method
A step of etching and removing a CVD deposited film deposited in a reaction tank constituting a semiconductor manufacturing apparatus in which a VD film is formed by a cleaning gas containing at least a halogen gas; and a step of etching and removing the CVD deposited film with a cleaning gas. After that, a step of flowing ammonia gas into the reaction tank to purge the cleaning gas remaining in the reaction tank is provided, and a purging method for a semiconductor manufacturing apparatus. 5. A step of inserting and mounting a semiconductor wafer in a reaction tank purged by the purging method of a semiconductor manufacturing apparatus according to claim 1, and the step of placing the semiconductor wafer in the reaction tank. And a step of forming a CVD film on a semiconductor wafer.